1. Field of the Invention.
The invention relates to a mold for producing tile-shaped floor elements for a double floor construction and to such a floor tile. 2. Description of the Prior Art
Double floor constructions are well-known and well established elements in modern offices, computing centers and places of production, which are in increasing demand due to the high flexibility they allow for in terms of the electrical supply of machines set up on such premises. Such a construction is generally a floor consisting of tile-shaped floor elements and the like which are borne via supports on a substructure. The journal "Fussbodenforum", No. 1, of January 1986, shows the newest prior art and says that in the case of unelastic floor coverings in the form of ceramic covering materials they are preferably applied on the construction site, whereas in the case of stone coverings and all others, including elastic ones such as carpeting, etc., the double floor constructions are produced as finished elements.
In view of the dimensions of 60.times.60 cm customary for an individual element for double floors, special demands are made on its loading capacity, its bow under load and the comprressive load in terms of point and surface load. Elastic coverings can make no contribution to carry static load, so that the double floor elements bearing such coverings must be designed so as to be alone capable of satisfying the required values. For this reason, one uses for such elements trough-shaped formations with high tensile strength and a filling with low tensile strength, i.e., a low modulus of elasticity, for example anhydride (German utility models nos. 78 04 148 and 81 06 740). Apart from the fact that such a construction is elaborate, these finished elements have a relatively large overall height with a corresponding dead weight. This is mainly due to the fact that the surface-ground core layer flush with the edge of the trough after setting is glued to the ceramic cover layer. This gluing also means that the compound tile-shaped floor element obtained has low shear strength, so that the cover tiles can gradually be detached due to the load on the floor.
It is known (German patent No. 33 45 620) to reduce the dead weight by adding spherical bodies of light construction material, but this increases production costs and does nothing to improve the overall height.
It is also known (German utility model no. 75 19 806) to use ceramic floor coverings for double floor constructions, but one uses synthetic-resin concrete reinforced by integrally cast grids. Such finished elements are elaborate to produce, heavy due to the reinforcement and have the great disadvantage of a corresponding overall height.
Another double floor construction is known (German laid-open print no. 36 03 232) formed of a compound consisting of a cover tile made of ceramic material with small layer thickness, a core layer made of rigid material with low specific gravity, and a thin bottom layer with high tensile strength, adhesives being used to ensure the bond between the compound layers. In view of the risk of breakage with ceramic tiles, adhesives with elastic properties are used. Since ceramic coverings, especially in the form of uniform tiles, for example as large as 60.times.60 cm, show a production-specific curvature of the tile plane, the adhesive is applied in corresponding dimensions and in excess to the initially prefabricated carrying element, when such tiles are laid, to compensate the curvature and ensure that the ceramic tiles are laid with a perfect fit.
According to another known construction (German utility Model no. 86 20 150), a sheet steel through filled with anhydride is provided to form a double floor tile, to which a paving tile is glued. The adhesive required serves at the same time as an edge band, i.e., a joint component, so that this adhesive must also show relatively elastic behavior.
Finally, tile-shaped floor elements for double floor constructions are known (German "auslegeschrift" No. 22 42 607) in the case of which a ceramic cover tile is placed on a trough and the compound is achieved by hardening of the core layer poured into the trough. No additional adhesive layer is required. Such a tile-shaped floor element is produced by placing the trough, which is open at the top, with its opening facing downward on a mold table provided with a recess for taking up the ceramic cover tile. Lateral flanges specially formed on the upper edge of the trough are overlapped by clamping means disposed along the periphery of the mold table to press the trough firmly onto the mold table. After the core layer has been poured in and hardened, the finished floor element can be removed from the mold table. This tile-shaped floor element also has a relatively large overall height, because the ceramic cover tile has its base on the trough. Furthermore, special molds are required for making the floor elements.
The known constructions, if capable of tansmitting sufficiently high moving and static loads, have a relatively large overall height, which leads to considerable problems in particular for the renovation of old buildings. Apart from this, the effort required to make these construction elements is relatively high due to the additional measures necessary for increasing their strength, which leads to accordingly high production costs. The mold for making such floor elements is also often elaborate itself, which again contributes to increasing the production costs. In the case of adhesives with elastic properties, the ability to transmit moving and static loads is limited.